Receiver set to type Beast will not show sync with Rx type Radarcape.
An actual beast, set to --input-type beast, will never show sync stats towards receivers of type radarcape. If set to dump1090, it will show sync.
The log file indicates that the receiver pair is used for solutions, so it actually has sync, but not shown in the sync stats table.
If 2 dump1090 system are both set to --input-type beast (for testing this issue, or by mistake), they will also not show sync with radarcapes, not with real beast systems, and not with each other, but with normal dump1090 systems....
(The client will auto-detect the correct format but has already informed the server of the manually set format, and as discussed, the on-the-fly format change is not implemented in mlat-server. )
What is the difference between beast and dump input formats?
There's no difference in input formats. The only real difference is that you might want different estimates of receiver clock stability/jitter depending on whether the receiver hardware is a rtlsdr or a Beast.